Archive for o-rings

Flashlight O rings and Grease

Posted in light, lubrication, technology with tags , , , on November 30, 2010 by marksun

O rings are used in most state of the art, high tech flashlights – the kind with the aircraft aluminum precision machined bodies.

The purpose of the o-rings are to form a tight, smooth fit for parts of the light that must move smoothly past each other, and to form a waterproof seal.  To have a reliable and smoothly functioning light,  keep the threads and o-rings clean and free of lint, dirt and moisture, and use the small amounts of grease on o-rings and threads.

Virtually all o-rings used in lights are made of synthetic rubber.  O rings for lights are seldom made of natural rubber (cost and durability) or silicone (cost and/or not the right mechanical properties).

  1. Virtually any silicone based grease or lubricant with or without PTFEs (or teflon) are safe on flashlight o-rings.
  2. Petroleum and mineral based greases are deemed to be less suitable because some synthetic and natural rubber o-rings are attacked by some petroleum based products.  carry risk in this application.  Manufacturers mainly recommend silicone based lubricants.
  3. WD-40 is petroleum based, is too light for this application, and may dry out the o-ring.

I use a couple of greases that I have in my collection of lubes:

  • Lube Gel – silicone grease with PTFE from Radio Shack (oem from a SYNCO).  This tube should last me about 40 years.
  • “Green Slime”,  a silicone PTFE grease used for RC car shock absorbers left over from my RC days.

In the short term, just about any grease will seem to work just fine.  The reason to consider what you use is that greases  tend to stick around for the long haul.  You don’t want the grease to melt down the o-ring to a gummy mess, since the time you discover it will be the time you will need your light the most.

Reference:  “Comprehensive Grease and Lube Thread” on the Candlepower Forum (CPF).